Thermochromic materials or pigments, i.e., pigments which change color at defined temperature ranges, are not themselves novel. For example, such thermochromatic pigments are used in children's bath toys or baby spoons to indicate when temperature of bath water or of child's food is too hot.
WO 01/12150 A1 (assigned to Unilever) discloses cosmetic compositions which comprise (i) an agent which will interact with water and cause a temperature change in the cosmetic; (ii) a thermochromatic substance which changes color in response to temperature change; and (iii) a pharmaceutically acceptable vehicle to deliver (i) and (ii) (e.g., moisturizers such as polyols). Although emulsifiers are optionally disclosed, the cosmetic compositions are not cleansing compositions (e.g., comprising minimum levels of surfactant cleanser). Further, the compositions require an agent which interacts with water to cause a temperature charge. In the subject invention, no such agent is required and the thermochromatic substance is simply a cue that a certain water temperature has been reached (and/or that benefit agent is released at said water temperature).
U.S. Pat. No. 6,290,977 to Friars et al. discloses flowable topical personal care compositions comprising (i) a thermochromatic pigment capable of color change between 20° C. and 40° C.; and (ii) a personal care active, said components (i) and (ii) being stably dispersed in a vehicle. There is no disclosure of a thermochromatic pigment in a solid aqueous bar (e.g., having 3 to 20% by wt., preferred 5 to 18% by wt. water). There is further no disclosure of concentrating the indicator dye (encapsulated or non-encapsulated dye) in regions or domains (e.g., in a polyalkylene chip) such that less of the dye can be used and/or where imperfect mixing of benefit agents (e.g., applied at lower temperature in the formulation/mixing process) can be masked and indeed presented as a positive.